Organic solvent based adhesives have been used for many years for joining objects made from PVC (polyvinyl chloride), CPVC (chlorinated polyvinyl chloride), ABS (acrylonitrile-butatdiene-styrene) and other thermoplastics. In use, the organic solvent partially dissolves or at least softens the surfaces to be joined, thereby achieving an intimate bond between these surfaces when the organic solvent evaporates. Normally, a small amount of thermoplastic resin, the same as or similar to the thermoplastic to be joined, is dissolved in the solvent, thereby producing a “solvent cement.” Additionally or alternatively, an acrylic resin can be included in the solvent cement, as acrylics adhere well to all three common plastics, i.e., PVC, CPVC and ABS. See, for example, U.S. Pat. No. 5,073,615 and U.S. Pub. App. No. 2006/0252865, the disclosures of which are incorporated herein by reference.
Many different organic solvents have been used for making organic solvent based adhesives. Examples include ketones, ethers, esters, amides, carbonates, organic sulfoxides, organic sulfones, organic sulfides, etc. Mixtures of different solvents are common. See, for example, the following patent documents, the disclosures of which are incorporated by reference: U.S. 2006/0030689, U.S. Pat. No. 6,372,821, U.S. Pat. No. 6,087,421, U.S. Pat. No. 5,495,040, U.S. Pat. No. 5,470.894, U.S. Pat. No. 5,422,388, U.S. Pat. No. 5,416,142, U.S. Pat. No. 5,376,717 and U.S. Pat. No. 5,252,634.
In accordance with this invention, it has been found that the amount of liquid organic solvent needed to produce an effective solvent cement, and hence the VOC content of such cements, can be reduced by including in the composition cyclododecanone (“CDDK”) or other oxygen and/or nitrogen-containing macrocyclic compound.
Thus, this invention provides a solvent cement for bonding plastics comprising (a) a corresponding polymer (i.e., a polymer which corresponds to the thermoplastic to be joined) selected from PVC, CPVC and ABS, (b) at least one polar organic solvent, (c) an optional sulfur containing solvent, (d) an optional co-solvent capable of at least partially dissolving or at least swelling the corresponding polymer, (e) an optional additional polymer selected from an acrylic polymer, a vinyl aromatic polymer, a vinyl pyrrolidone polymer, and mixtures thereof, and (f) at least one oxygen and/or nitrogen-containing macrocyclic compound.
In addition, this invention also provides a process for bonding PVC, CPVC or ABS plastic pipe and other molded articles to one another, the process comprising applying a solvent cement to the surfaces to be bonded and then bringing these surfaces into contact with one another, wherein the solvent cement comprises (a) a corresponding polymer selected from PVC, CPVC and ABS, (b) at least one polar organic solvent, (c) an optional sulfur containing solvent, (d) an optional co-solvent capable of at least partially dissolving or at least swelling the corresponding polymer, (e) an optional additional polymer selected from an acrylic polymer, a vinyl aromatic polymer, a vinyl pyrrolidone polymer, and mixtures thereof, and (f) at least one oxygen and/or nitrogen-containing macrocyclic compound.